The invention relates generally to level sensors for a metering system container, and more specifically, to a pair of sensors configured to physically contact material within the metering system container to control a flow of material into the container.
In agricultural settings, various types of applicators are employed to deliver liquid or dry fertilizer and/or herbicide to the surface of a field. In a typical configuration, applicators include a material distribution system mounted on a vehicle. The material distribution system is configured to store, meter, and distribute fertilizer and/or herbicide to the field. For example, a material distribution system configured to distribute dry fertilizer generally includes a material holding bin for storing the fertilizer. The material distribution system also includes a metering system configured to receive material from the material holding bin and transfer specific quantities of material to a delivery system. The delivery system typically includes booms that extend laterally outward from the applicator to delivery material to the soil.
Metering systems generally include a storage container configured to receive and store material from the material holding bin prior to transferring measured amounts of material to the delivery system. The storage container typically includes one or more sensors configured to determine a level of material within the container. When the material level approaches a top of the storage container, the sensors will detect this condition and disengage or temporarily interrupt transfer of material from the material holding bin. Sensors will also detect when the material drops below a predetermined level and engage or restart transfer of material from the material holding bin to prevent the metering system from exhausting its supply of material.
Certain metering systems are configured to receive material from the bottom of the container. Such configurations typically employ a float switch configured to float on the surface of the material to determine its level within the storage container. However, more recent metering system configurations employ storage containers configured to receive material from the top. Because conventional float switches are not particularly effective in such arrangements, top loaded metering systems typically employ a photoelectric sensor configured to optically observe the level of material within the storage container. However, photoelectric sensors will not function properly if dust from the material obscures the optical measurement. Similarly, damp material may adhere to the sensor, thereby blocking visual observation of the material level within the storage container. Such dust and moisture are often present in agricultural field settings. If the sensor does not detect that the material has dropped below a minimum level, the metering system may not engage transfer of material from the material holding bin. At that point, the metering system may exhaust its supply of material, thereby resulting in uneven distribution of material across the field.
Consequently, it may be desirable to provide sensors capable of measuring material level within the storage container without becoming ineffective in the presence of dusty or damp conditions.